Control of steady-state stability of 500 kV transmission lines in the National Electrical Networks of Kazakhstan using PMUs data

摘要

It is planned to create stability control system in real time by applying WAMS technology for maximum use of 500 kV transmission lines capacity. The pilot project of such system has been realized on two phasor measurement unit devices installed on 500 kV substations “Ekibastuzkaya” and “Alma”. At the moment in the National Electrical Networks (NEN) of Kazakhstan the modes monitoring has been realized by the Wide-Area Measurement System (WAMS) by means of the current measurements of a mutual angle, voltage, current, frequency and power. And inter-area and local low-frequency oscillations (LFO) have been observed as well. Monitoring results and the analysis of LFO natural frequencies oscillations and their amplitude values in the normal diagram on the “North-South” transit of NEN of Kazakhstan are given. Problems of algorithm elaboration of stability assessment based on mode parameters received from real-time systems are considered. Stability monitoring is carried out by monitoring of a Jacobi matrix sign according to the data received from PMU devices. Controlling the sign of the Jacobi matrix determinant or the Jacobian with weighting of the regime from a known steady state it is possible to determine the regime transition to an unstable state when the sign of the Jacobian changes. For comparison, stability of the equivalent circuit of the NEN of Kazakhstan was determined by two methods: the method of successive iterations of Newton and the method of the Jacobian sign control. The analysis results show that the mode divergence at the use of the method of successive iterations of Newton and the method of stability control with the Jacobi matrix happens under the same mode parameters.